What is Storage Spaces Direct?

Storage Spaces Direct (S2D) is a new technology of distributed data storage introduced in Windows Server 2016 Datacenter and Windows Server 2019 Datacenter. With S2D the local disks of several servers can be organized into fault-tolerant and scalable storage, protected from both individual disk and entire server failure. The price of such software-defined storage (SDS) is much lower than the cost of organizing a full SAN or NAS. In addition, simple scaling and the ability to use a variety of drives (including SSDs and NVMe) allows achieving significant performance and efficiency.

Benefits of Storage Spaces Direct

By making it possible to use industry-standard servers with internal drives and eliminating the need for a common SAS structure, S2D reduces complexity, increases scalability, and provides the flexibility in utilizing storage devices that were previously unavailable. On top of that, S2D also has many other advantages.

The convenience of use

You only need 15 minutes to go from standard Windows Server 2016-based servers to the first Storage Spaces Direct cluster. Clicking one checkbox enables System Center users to deploy the solution.

High performance

With flash or hybrid drives, Storage Spaces Direct allows you to easily handle more than 150,000 mixed random 4k IOPS per server. The delay is minimized thanks to the built-in hypervisor architecture, read/write cache, and support for advanced NVMe drives that are installed directly on the PCIe bus.

Fault Tolerance

Storage Spaces Direct supports fault-tolerance. When disks fail, corrupted data is automatically restored on the remaining disks. Effective technology ensures continuous availability in case when drives, servers, or components fail.

Accelerated Erasure Coding System

Local Reconstruction Codes and real-time tiering inherent to erasure coding provides 2.4 times greater storage efficiency. The increase in efficiency applies to hard disk drives and mixed hot/cold workloads. This reduces the CPU resources consumed, and they can be used where they are needed most - in the virtual machines (VM).

Comprehensive performance management

Storage QoS Controls allows you to check overloaded VMs for compliance with the minimum and maximum per-VM IOPS limits. The Health Service is an intelligent built-in diagnostic mechanism that enables administrators even with basic technical knowledge to monitor and manage the system every day.


Storage Spaces Direct can scale from 2 to 16 servers. You can add servers as needed and simply rebalance the data to make the best use of additional resources.

S2D Deployment Options

Storage Spaces Direct architecture provides customers with the choice to deploy an infrastructure either as converged or hyperconverged.

Storage and compute in separate clusters

In converged deployments, a Scale-out File Server (SoFS) is placed on top of Storage Spaces Direct to provide network-attached storage over SMB3 file shares. Compute and storage separated scenario increases IT infrastructure scalability and ensures independent compute and storage resource management.

One cluster for compute and storage

The nub of Storage Spaces Direct hyper converged deployment is to run Hyper-V VMs or SQL Server databases directly on storage servers, where files are stored on the local volumes. In this way, users gain simplified access to the file server without a need to set permissions and thus, reduce hardware deployment costs.

Storage Spaces Direct in Use

Microsoft S2D represents a further development of the Storage Spaces technology. It integrates with up-to-date features to create the Windows Server SDS stack, including SoFS (SMB 3.0), Cluster Shared Volume File System (CSVFS), Storage Spaces, and Failover clustering. Also, Storage Spaces Direct has a completely new feature called Software Storage Bus. It spans an S2D Hyper-V cluster and sets up a software-defined storage factory where all servers can see each other's local drives. Storage Spaces Direct uses new Resilient File System (ReFS), which significantly speeds up operations with VHDX files, such as creating, expanding, and combining checkpoints.

The operating principle of S2D is that it combines local disks of nodes from a Hyper-V cluster into Storage Pools. These pools enable to create virtual volumes and use them as Cluster Shared Volume (CSV) for storing files of Hyper-V VMs and file layers of SoFS servers. This being said, storage size can be expanded by simply adding a new server or drive to S2D.

Storage Spaces Direct is extremely easy to use. All you need to start working with it is to meet the following minimum requirements:

  • Windows Server 2016 Datacenter Edition;
  • 2 to 16 servers in a Hyper-V cluster with available local-attached SATA, SAS, or NVMe drives;
  • At least 10GbE networking connectivity;
  • RDMA is recommended;
  • Memory for Windows Server, VMs, and other apps or workloads.

Microsoft Storage Spaces Direct is a unique opportunity to organize disk space for multi-node fault-tolerant systems. Converged or hyperconverged architecture drastically simplifies the acquisition and deployment of solutions. At the same time, such features as caching, tiered storage, and clearing coding, together with the latest technologies such as RDMA network and NVMe drives provide unrivaled efficiency and performance.

Storage Spaces Direct vs. StarWind Virtual SAN (VSAN) - What to deploy

Storage Spaces Direct may seem a perfect solution for an IT infrastructure when it comes to the unlimited company’s budget. But there is one catch. When using S2D, the user is always limited by a strict SLA. Therefore, there is near-zero freedom of choice of hardware resources. With StarWind VSAN, you are free to choose which hardware and drives to use - SATA, SAS, NVMe, or HDD. This brings significant savings to your IT environment and is a win-win option for SMB and ROBO.

Another aspect is management. Although Microsoft offers Windows Admin Center, a convenient tool for managing your Windows Server environment, you must also be on a first-name basis with PowerShell to fix all the problems originating in your failover cluster. However, the reality is that almost all the tasks you can perform in a User Interface (UI) without going deep into the complexity of a command-line interface (CLI). StarWind Management Console is the Graphical User Interface (GUI) part of the program that helps to monitor and control all storage-related operations at the touch of a button. With StarWind, you don’t puzzle head over PowerShell administration, but simply manage your cluster through a comfortable UI.

In addition, it is no secret that the Windows-native SDS solution is only included in the most expensive license edition, while the licensing terms themselves are limited and rigid. With StarWind, you get a flexible licensing scheme where there are no restrictions on the number of sockets, cores, or features. Deploying StarWind VSAN, you get transparency in your IT infrastructure operation.

Please fill out the form below to download the product. An installer link together with the license key will be sent to the e-mail address that you’ve specified. You may check the Free vs. Paid document if you are unsure about which StarWind Virtual SAN version you would like to try. Aside from this, there is a totally unrestricted NFS (Not For Sale) version of StarWind VSAN available for certain use cases. StarWind Virtual SAN for Hyper-V release notes are available here.